A demand for electronic devices having long-term reliability, flexible shapes, and a curved display has been added to the longstanding demands for larger and lighter electronic devices. To meet such demands, film substrates have been used that are composed of transparent plastics instead of glass substrates, which are heavy, fragile, and unsuitable for use on large areas.
Unfortunately, film substrates composed of transparent plastics have inferior gas barrier properties compared to glass substrates.
For example, a substrate having inferior gas barrier properties may allow permeation of water vapor and oxygen, and thus may lead to deterioration in an electronic device, for example.
Typically, a film having gas barrier properties is formed on a film substrate and serves as a gas barrier film. For example, known gas barrier films that serve as wrapping materials for wrapping objects that require a barrier against gases and are provided in liquid crystal displays are formed through vapor deposition of silicon oxide or aluminum oxide on a film substrate.
Unfortunately, the vapor deposition described above leads to a water vapor barrier rate of approximately 1 g/m2·24 h at most.
Recent development of high definition large displays requires superior gas barrier properties of film substrates. Specifically, the water vapor barrier rate required is approximately 0.1 g/m2·24 h for liquid crystal displays, and approximately 10−6 g/m2·24 h for organic electroluminescence elements.
To meet the requirement of a high water vapor barrier rate, gas barrier layers have been disclosed that include a barrier layer formed through polymer multilayering (PML) (for example, refer to PTL 1).
Gas barrier films have been disclosed that can be bent without degradation in gas barrier properties for water vapor and oxygen, as well as barrier properties (for example, refer to PTL 2).